HOW TO DO A VOLTAGE DROP TEST ON STARTING CIRCUIT

[JUSTINTIME]

HERE U GO
FINDS OUT IF U HAVE TOO MUCH RESISTANCE SOMEWHERE IN THE CIRCUITS

 

[j_martin]

Re: HOW TO DO A VOLTAGE DROP TEST ON STARTING CIRCUIT

voltages 1-5 will always equal 6. Any difference is measurement error, compounded by multiple measurements.

Voltage 6 - voltage 5 is total voltage drop. Any of the other readings across wires, grounds, or solenoids should be very low. If it's high, the wire is sized wrong, connections are dirty, the solenoid is dying, etc.

hope it helps
John

 

[Texasmark]

Re: HOW TO DO A VOLTAGE DROP TEST ON STARTING CIRCUIT

Just adding a tidbit to justintime's explanation.


My midsized engine is stated to require up to 120 amperes (from a 12v battery) to start.

To give you an idea as to what justintime is saying, any resistance in the circuit (including internal to the battery) will cause you big problems.

Example: At 120 amperes, 0.1 ohm will drop (Amps x Resistance = Volts.......120 x 0.1 = 12v.) That's the full battery static terminal voltage. :%

So theoretically, if your engine did require the full 120 amperes (larger engines require more) and you had 0.1 ohms of resistance in the circuit (which is nothing), as soon as you closed the starting solenoid, the bendix would spin up, hit the flywheel and disengage immediately, as there would be 0 volts left in the circuit to spin the starter under the load of the engine.

Hygiene is that important.

HTH,

Mark

 

[j_martin]

Re: HOW TO DO A VOLTAGE DROP TEST ON STARTING CIRCUIT

Usually when us electrical types talk about high current, low voltage circuits, resistance is in milliohm. (1 milliohm = 0.001 ohm) It can't be measured reasonably with any ordinary test lead type instrument, like a multimeter or a fluke, as the lead resistance is significant. It is calculated by measuring the current and the voltage drop. V/A * 1000.

Clean connections and short heavy leads are the key to good starting.

 

[JUSTINTIME]

Re: HOW TO DO A VOLTAGE DROP TEST ON STARTING CIRCUIT

also, u must go to the terminals not the wires

 

[bruceb58]

Re: HOW TO DO A VOLTAGE DROP TEST ON STARTING CIRCUIT

Usually when one refers to himself as an "electrical type"...I begin to worry!

 

[j_martin]

Re: HOW TO DO A VOLTAGE DROP TEST ON STARTING CIRCUIT

Usually when one refers to himself as an "electrical type"...I begin to worry!

I've been tinkering with electricity for about 50 years. The most formal school I've received is Navy ETA school. (Electronics technician) in the 60's.

I've made my living in electronics, usually at the engineering level, and several other disciplines also, including mechanical and thermodynamics. I'm talking design level electronics, and leading edge phase change thermal design, along with more mundane but useful things like relay logic multifuel boiler controls.

I like to say that I can usually find a common sense solution to a problem because I am unencumbered by knowledge.

If I begin to ramble, or start to speak in acronyms that are meaningless to you, just slap me, I'll be OK

Do you really have a million dollars?

 

[bruceb58]

Re: HOW TO DO A VOLTAGE DROP TEST ON STARTING CIRCUIT

The most formal school I've received is Navy ETA school. (Electronics technician) in the 60's.

I can believe that...it shows.

I am unencumbered by knowledge.

I can believe that...it shows.

Do you really have a million dollars?

Yep!...a few of them.

 

[j_martin]

Re: HOW TO DO A VOLTAGE DROP TEST ON STARTING CIRCUIT

d

 

[Texasmark]

Re: HOW TO DO A VOLTAGE DROP TEST ON STARTING CIRCUIT

Well goodie for you Bruce. Looks like EE's do better in Sunny Ca. than in other parts of the USA. EE and Machine Design must have missed CA in their salary survey's.......unless you inhereted it or made it off the stock market. :|

You might try spending a little of it, return to school and study something like "Getting Along with Others 101".

Mark

 

[bruceb58]

Re: HOW TO DO A VOLTAGE DROP TEST ON STARTING CIRCUIT

Well Mark...since you never saw the reason why j_martin asked me that last question, you wouldn't know why I gave him the answer I gave him...would you?

 

[eurolarva]

Re: HOW TO DO A VOLTAGE DROP TEST ON STARTING CIRCUIT

I agree with Texasmark about Bruce. You give someone some advise here and the all mighty engineer tells you your an idiot. I have worked with engineers at honeywell that could not troubleshoot a toaster. Just because you can design it does not mean you can fix it.

 

[bruceb58]

Re: HOW TO DO A VOLTAGE DROP TEST ON STARTING CIRCUIT

eurolarva...did they use a battery charger to troubleshoot their toaster?

 

[eurolarva]

Re: HOW TO DO A VOLTAGE DROP TEST ON STARTING CIRCUIT

Nope. They used a marine battery and it exploded